Recent trends in electronic devices and electronic equipment call for portability and miniaturization (that is for light and small-size devices). In order to attain the miniaturization goals and to improve serviceability, not only active and passive parts, but also electromechanical elements (such as connectors and switches) undergo considerable improvements, especially in the field of home electronics. SMT-type elements are especially effective for these purposes and they are widely used in the devices where small size and high mounting density are especially important. As it is well known in the art, the surface mounting technology comprises applying a layer of soldering cream on the pads of the base boards or printed circuit boards to which terminals or soldering tails of electronic elements are pressed against the pads. After that, the pads are heated (for example by infra red radiation) to a temperature above the melting point of the solder, thus soldering the two elements together.
An example of a conventional surface mounted connector (below, SMT connector) can be found in the Japanese patent publication No. 90-28236 related to U.S. Pat. No. 4,583,807 filed by AMP Incorporated. This connector has a narrow long housing with several rows of contacts which are fixed to the base board. Soldering tails of these contacts are bent in such a manner that they form a surface coincident with that of the soldering pads formed on the base board. However, with an increase in the number of contacts and in their density, it becomes difficult to keep all soldering sections of the soldering tails in one plane. In addition, there is danger that the contacts will be deformed during the handling of the connectors manually or by means of robotics arms.
A solution making it possible to eliminate this disadvantage which comprises the use of a part determining the position of the soldering tails to align them with the soldering pads of the base board is known in the art. An example of such a solution can be found in the Japanese patent publication No. 89-279581 related to U.S. Pat. No. 4,583,807 filed by AMP Incorporated. In this specific example, soldering tails of contacts arrayed in two rows are bent in a certain configuration as shown in FIGS. 5 and 6.
This conventional SMT connector comprises a housing 10 and two rows of contacts 11 inserted in the contact channels 14 provided in the housing. Part 21 restricting soldering tails is inserted in the recesses 25 made in the opposite end walls 16 in such a manner that it (the part 21) can move. This part 21 restricting the soldering tails has one row of the openings 22 into which free ends of the soldering tails 18 of the lower contacts 11 are inserted, and channels (or grooves) 23 into which free ends of the soldering tails 18 of the upper contacts 11 are inserted. This configuration makes it possible to keep all the soldering portions 19 of the soldering tails 18 of the contacts 11 aligned with the soldering pads 30 of the base board.
However, the assembly of the SMT connector shown in FIGS. 5 and 6 represents certain difficulties. The insertion of the soldering tails 18 of the lower row contacts 11 into the openings 22 of the housing 10 and the correct placement of the soldering tails 18 of the upper row contacts 11 in the channels 23 made in the bottom of the part 21 restricting movement of the soldering tails becomes an extremely difficult, time-consuming operation, especially with an increase in the number of the soldering tails or in their density (in other words, in the SMT connectors intended for miniaturized devices having a high density of element mounting).
Therefore, the purpose of this invention is to offer an SMT connector in which it is possible to maintain coplanarity of the soldering tails of a number of contacts and, at the same time, to provide appropriate pressure on the soldering tails when they are pressed against the soldering pads of the base board during soldering operation.
Another purpose of this invention is to offer an SMT connector which facilitates mounting operations by making it unnecessary to pay too much attention to the handling of the connectors.